The effect of prolonged cerebral hypoxia after head trauma will be studied by evaluating the pattern of recovery and outcome by means of neurological and neuropsychological examination. A unique group of patients who are intubated and ventilated soon after injury are available to the study through the Life Flight Helicopter Program and can be compared to patients intubated after a longer delay or patients suffering cerebral hypoxia from other conditions. Patients will be evaluated comprehensively in order to define pathophysiology of head trauma and spinal cord trauma. The data will be maintained in a computer facility to allow retrieval and statistical analysis in order to predict outcome as early and reliably as possible. Information will be obtained from neurological examination, physiological monitoring involving intracranial pressure and electrophysiological parameters, neuropsychological testing, cardiovascular and pulmonary measurements, evaluation of coagulopathies and thrombiphlebitis, and studies in metabolism and nutrition. Be defining criteria for predictability, it will subsequently be possible to evaluate efficiently other selected treatment variables.